1. Field of the Invention
The present invention relates to a photographic light-sensitive material having a novel silver halide emulsion and a method of developing the same. 2. Description of the Related Art
Considerable effort has been expended to suppress fogging of a silver halide emulsion and to increase its photographic sensitivity. In addition, a reduction in the time required to carry out all the developing steps such as development, bleaching, and fixing is a practical great merit and is one of important targets in performance improvement of silver salt photography. Minimization of changes in photographic characteristics caused by variations in processing conditions also provides a great merit. Conventionally, a silver iodobromide emulsion subjected to gold-plus-sulfur sensitization is practically used as a high-speed photographing material. However, when a silver iodobromide emulsion is used, a developing time cannot be reduced because development is significantly restrained by iodide ions or bromide ions, released during development. In addition, since these ions are stored in a processing liquid, variations in photographic characteristics are increased. Also, these ions adversely affect a bleaching step. Furthermore, since the silver iodobromide emulsion has low solubility in water, a long period of time is required for fixing. On the contrary, when a silver chloride emulsion having a high silver chloride content and containing substantially no silver iodide is used, the time required for development, bleaching, and fixing steps can be reduced, and changes in photographic characteristics caused by variations in the processing conditions can be minimized. In a high silver chloride emulsion, cubic grains having a (100) crystal plane are normally formed. When these grains are chemically sensitized, they tend to be fogged. This fog is significant especially when the grains are subjected to gold sensitization. More specifically, fogging poses a problem in practical use in a developer having high activity for rapid development, especially, in a color developer. Storage fog generated when a light-sensitive material is aged also poses a practical problem. When a high silver chloride emulsion is exposed at high intensity for a short period of time, reciprocity failure is increased. This is another drawback of the high silver chloride emulsion when it is used as a high-speed photographing material. Although it is known that a regular crystal high silver chloride emulsion having a (111) crystal plane can be prepared by a special method, not so many studies have been made so far. In addition, almost no high silver chloride emulsion for use in a high-speed photographing material is known. The Journal of Photographic Science, Vol. 21, P. 39 (1973) only reports that silver halide grains having the (111) crystal plane can be prepared using dimethylthiourea, but does not refer to its photographic characteristics. In the International Congress of Photographic Science (Rochester 1978), Wyrsch reports that grains having the (111) crystal plane can be prepared using a cadmium compound and ammonia. He reports that no large difference in photographic sensitivity is found between grains having the (111) crystal plane and those having the (100) crystal plane when they are compared using a sulfur-sensitized emulsion but the grains having the (100) crystal plane have slightly higher sensitivity Japanese patent application (OPI) No. 55-26,589 discloses that silver halide grains having the (111) crystal plane can be obtained by supplying a merocyanine dye during grain formation. However, this patent specification discloses not high silver chloride grains for use in a high-speed photographing material but effectiveness of limiting a dye addition method regardless of a crystal plane or a grain composition. In this manner, it is well known that a high silver chloride emulsion is a preferable material for reducing a time required for processing steps. However, it is considered that manufacture of a high-speed photographing material of high silver chloride is technically difficult because fog is significantly increased and the high-intensity reciprocity failure is large when the high silver chloride emulsion is chemically sensitized to achieve high sensitivity. In addition, it is also well known that fog is increased when gold sensisization is performed. That is, a technique for sufficiently performing gold-plus-sulfur sensitization, which is an essential treatment for a high-speed photographing material, to the high silver chloride emulsion has not been realized. Therefore, almost no examples of a high-speed photographing material using the high silver chloride emulsion are known.